Blood pressure information measurement devices obtain blood pressure information of a measurement subject. The blood pressure information obtained by such blood pressure information measurement devices includes various types of information related to the circulatory system, such as a systolic blood pressure value (a maximum blood pressure value), a diastolic blood pressure value (a minimum blood pressure value), an average blood pressure value, a sphygmogram, pulse, AI (Augmentation Index) value, and the like of the measurement subject, and so on. Stress on the heart, changes in the hardness of arteries, or the like can be understood based on this blood pressure information. A blood pressure information measurement device is used in the early detection, prevention, treatment, and so on of circulatory system conditions.
Generally speaking, a blood pressure information measurement device cuff (called simply a “cuff” hereinafter) is used in the measurement of blood pressure information (see JP H5-39504U (Patent Literature 1)). The cuff contains a fluid bladder for pressurizing the body (an artery). The cuff is a band-shaped member having an inner cavity, and can be wrapped around a part of a body such as an upper arm.
In a blood pressure information measurement device used to measure blood pressure values such as a systolic blood pressure value or a diastolic blood pressure value (called simply a “sphygmomanometer” hereinafter), the cuff is wrapped around the surface of part of the body. A fluid such as air, a liquid, or the like is injected into or exhausted from the fluid bladder enclosed within the cuff. The fluid bladder is inflated by injecting a fluid into the fluid bladder. On the other hand, the fluid bladder is deflated by exhausting the fluid from the fluid bladder. Changes in the pressure within the fluid bladder produced when the fluid bladder inflates or deflates are registered as an arterial sphygmogram or a blood pressure value.
A typical cuff includes an air bladder serving as the fluid bladder and a band-shaped outer cover. The outer cover contains the air bladder. A surface fastener is provided on the surface of the outer cover. A loop-shaped ring is attached to one end of the outer cover in the lengthwise direction thereof. The cuff is formed into a ring shape by passing the other end of the outer cover in the lengthwise direction thereof through the loop-shaped ring and bending that other end of the outer cover back.
The measurement area is then inserted into the area of the outer cover that has been formed into a ring shape. The cuff is thus wrapped around the measurement area. The outer cover is tightened down upon the measurement area, and is held in a fastened state by the surface fastener. As a result of this fastened state, the air bladder is anchored to the measurement area. The cuff, and a sphygmomanometer provided therewith, are capable of measuring blood pressure information.
Incidentally, with a typical cuff, it is easy for the outer cover to rotate in the circumferential direction thereof when the outer cover is tightened onto the measurement area. If the outer cover rotates in the circumferential direction, it becomes necessary to rotate the outer cover in the opposite direction as the direction of the original rotation and tighten down the outer cover again in order to obtain the desired tightened state for the cuff. Typically, the stated rotation in the circumferential direction and the rotation in the opposite direction as that rotation are repeated multiple times.
Because the rotation in the circumferential direction and the rotation in the direction opposite to the circumferential direction are repeated multiple times, in the case where, for example, the blood pressure value is measured on a day-to-day basis, it is difficult to recreate a predetermined tightened state for the cuff. As a result, variations appear in the measured values obtained through day-to-day measurements, which makes it difficult to measure the blood pressure information in an accurate and stable manner.    Patent Literature 1: JP H5-39504U